Antimicrobial barrier coatings and methods of use

ABSTRACT

Barrier/sealer compositions impart at least biostatic activity to porous substrates, particularly architectural building materials, such as wood products, providing extended protection against the development of damaging fungi, such as mold, mildew and yeasts, as well as bacterial infestation. The protective sealer compositions comprise at least one antimicrobial agent, such as a fungicide and a film forming combination comprising a continuous film forming polymer and a water repellent compound. The spectrum of activity can also be potentiated to impart expanded biocidal activity to effectively kill and clean infected porous substrates and extend the useful life expectancy of architectural building materials by the introduction of other additives, including peroxide and antibacterial quaternary ammonium compounds.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application 60/516,021, filed Oct. 31, 2003.

TECHNICAL FIELD

The present invention relates generally to protective barrier or sealer coating compositions and methods of use for porous surfaces, and more particularly, to compositions for preventing and/or treating surfaces of building and construction materials, including wood products, gypsum board, ceiling tile, brick, concrete, etc., from infestation by microorganisms.

BACKGROUND OF THE INVENTION

Fungi, particularly mold, mildew and yeasts, including bacteria infestations in homes and commercial buildings have been an ever increasing health problem. Interior environments of homes, schools, hospitals and commercial buildings, new and old, commonly experience dampness and airborne particles of dust which can serve as carriers of microorganisms, such as bacteria, viruses and fungi. If left untreated they can lead to the development of damaging mold and mildew and other potential health hazards in walls, ceilings, flooring, air ducts, etc. These structures are commonly built from products, such as framing lumber, plywood and particle board sheeting, wallboards, roofing, flooring, cement building blocks, brick, and other building materials. Such infestations, if not corrected can lead to illnesses and diseases among individuals who occupy these buildings.

Heretofore, it was common practice to treat affected buildings, e.g., homes, commercial buildings, schools, hospitals, etc., after the problem was detected. This would often entail replacement of affected building structures, including ceiling tiles, wallboards, paneling, and so on, at considerable expense. A less costly alternative to replacement of affected building structures recently has been the application of environmental cleaning solutions, such as disclosed by U.S. Pat. No. 6,530,384 to Meyers et al. The solutions and methods of Meyers et al have proven to be an effective, more economic alternative for remediating affected buildings while avoiding the more costly approach of replacement of building structures.

While the solutions/methods of Meyers et al have been a cost effective alternative in the environmental treatment of building surfaces, they were developed principally for remediation of buildings already infected with damaging mold, mildew and bacteria. That is, the patented solutions have been applied to building architecture as a reactive treatment to microbial contamination.

It would, however, be desirable to have an effective proactive means for preventing the development of microorganisms, particularly fungi and bacterial infestation into building architecture, including surfaces/structures of homes, schools, hospitals and commercial buildings beforehand by applying a cost effective high penetrating solution to building materials before the actual construction phase commences, or after a home or other building structure is framed in, for example. That is, it would be highly desirable to have architectural construction materials, such as lumber products, e.g., framing lumber, including plywood, particle board, gypsum wallboard (drywall), ceiling tiles, cinder block, brick, etc., pretreated with a solution suitable for penetrating into their porous structures, as a preventive means to later development of a broad range of damaging microorganisms, particularly fungi, such as mold, mildew and yeasts, as well as bacteria.

SUMMARY OF THE INVENIION

Accordingly, it is a principal object of the invention to provide for protective, high penetrating biostatic sealer compositions for application to building/architectural construction for long term inhibitory activity from potentially damaging microorganisms that can adversely affect interior building environments and their occupants.

It is yet a further principal object of the invention to provide novel biocidal barrier compositions especially for application to infected architectural building structures, particularly porous structures, comprising wood/cellulosic materials, such as framing lumber, plywood products, particle board products, wood flooring, wood based roofing products, wallboard products comprising gypsum (drywall/sheetrock) products, ceiling products, such as porous Fiberglass® products, like ceiling tiles; cement-containing products, including concrete, cinder blocks, and brick, to name but a few.

It is yet a further object of the invention to provide for novel compositions comprising combinations of biocidally active ingredients for effective cleaning and treatment of porous architectural construction products, such as wood and other forest products which have developed mold and mildew, for example, during aging and storage processes for effective remediation and long term inhibitory activity from such damaging microbes.

Generally, the protective barrier compositions of the invention comprise at least one antimicrobial agent, a plasticizer, a surfactant, a continuous film forming polymer and a water repellent compound. In particular, the protective barrier compositions include at least a fungicidal agent as the antimicrobial agent, a nonionic type surface active agent, a water based vinyl resin as the continuous film forming polymer and a waxy compound as the water repellent material.

The protective barrier compositions of the invention may include, for example, a benzimidazole or other known class of antifungal agents; a vinyl acrylic latex as the continuous film forming polymer; a paraffin oil, for example, as the waxy compound. The pH of the compositions are preferably adjusted to about a neutral range, e.g., about 6.0 to 8.0, and more preferably, about 7.0.

It is yet a further aspect of the invention to provide methods of using the foregoing protective barrier compositions as substrate sealers in a biostatic capacity to prevent infestations of microorganisms, e.g., broad range of bacterial infestations and fungi, including the development of yeasts, molds and mildews. The protective barrier compositions may be applied to various surfaces by contacting with a biostatically effective amount by painting, rolling or spraying means onto architectural building materials, such as drywall (sheetrock), lumber and cement-containing substrates, e.g., concrete, building blocks and brick, either before the construction phase commences, during the construction phase, or after construction is completed, e.g., after a building, home has been framed-in, especially interior regions.

The methods of the invention also contemplate embodiments wherein the novel solutions are applied to porous substrates for treating those already having infestations of microorganisms, through application of a biocidally effective amount to the affected substrates, as previously disclosed.

These and other features and advantages will become apparent after a reading of the following more detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The high penetrating barrier solutions of the invention comprise an antimicrobial agent as the principal active ingredient present in the solution in a biocidally sufficient amount, preferably a benzimidazole, such as 2-(4-thiazolyl)benzimidazole. This is but one representative member of a family of useful fungicides.

More specifically, the foregoing antimicrobial agent is present in an amount ranging generally from about 0.01 to about 0.10 percent-by-weight, and more particularly, in an amount ranging from about 0.02 to about 0.06 percent-by-weight.

The other ingredients of the solutions of the invention greatly enhance both the effectiveness in terms of penetration into the porous substrate and long term performance of the antimicrobial agent. For example, in the case of forest products, the solutions of the invention preferably include a plasticizer in a sufficient amount to prevent cracking of the barrier coating due to the natural aging and drying of wood. A plasticizer, such as tributyl phosphate added in an amount ranging from 0.50 to about 4 percent-by-weight, and more specifically, in an amount ranging from about 1.0 to about 3 percent-by-weight will maintain the flexibility of the barrier coatings and minimize the potential for fracturing.

A surfactant is a further significant ingredient of the barrier solutions of the invention for maximizing penetration of the barrier coating composition into the porous substrate, i.e., active ingredients into the pores of the wood or other substrate product. While other types of surfactants may be used, such as amphoteric, anionic and cationic types, nonionic surfactants are preferred because they offer the greatest compatibility with other ingredients of the solution. The surfactant is useful in aiding in the reduction of surface tension allowing wetting of the substrate for more effective impregnation of the antimicrobial agent into the porous structure while providing more effective leveling of the coating at the time of application.

Representative useful surfactants include: ethylene oxide/propylene oxide copolymers, and more specifically, ethylene diamine reacted block copolymers available from BASF under the trademarks Tetronic and Pluronic. Other nonionic type surfactants include the ethoxylated fatty alcohols containing, for instance, from 11 to 15 carbon atoms and from 3 to 40 moles of ethylene oxide, which are available from Union Carbide under the Tergitol trademark. The surfactant may be used in an amount sufficient to enhance penetration of the antimicrobial agent into the substrate, and more specifically, 0.10 percent to about 3.0 percent-by-weight, and more preferably 0.5 to 2.0 percent.

Representative amphoteric surfactants are the imidazolinium derivatives prepared from 2-alkyl-1-(2-hydroxyethyl)-2-imidazolines and sodium chloroacetate. This class of surfactants is commercially available under such Trademarks as Miranol from Rhone-Poulenc.

The cationic surfactants may include polyethoxylated cationic types, for example. Cationic types include the amines consisting of aliphatic and mono, di and polyamines derived from fatty and rosin acids. They may include mainly primary, secondary and tertiary monoamines with C₁₈ alkyl and alkenyl chains. Other cationic surfactants include the oxygen-containing amines. This includes the amine oxides, ethoxylated alkylamines, 1-(2-hydroxyethyl)-2-imidazolines, for example.

Other principal ingredients of the barrier coating compositions are the continuous film-forming ingredients which are responsible for long term protection of the treated substrate. The continuous film forming ingredients actually provide a protective barrier for the substrate. The continuous film-forming ingredients preferably comprise a polymeric coating compound, such as a vinyl acrylic latex or other water based vinyl resin which act as a binder. The polymeric binder is generally used in a major amount, ranging from about 30 to about 60 percent-by-weight, and more specifically from about 40 to about 50 percent-by-weight.

As a second component of the continuous film-forming portion of the barrier coating composition is a waxy substance, such as paraffin oil introduced to impart water repellency to the above polymeric film. Paraffin oil, or other waxy substance is used in an amount ranging generally from about 1.0 to about 6.0 percent-by-weight, and more preferably, from about 2 to about 4 percent-by-weight.

Optional ingredients of the barrier coating composition may include such materials familiar among persons skilled in the art, and comprises rheology modifier, added generally in an amount ranging from about 1.0 to about 4 percent-by-weight, which has a thickening effect for preventing possible phase separation of the ingredients. Ammonia may be added as a weak base to adjust the pH of the coating composition to a about 7.0, if needed. A bactericide, such as Biocheck® available from Bayer can be added to the composition as an in-can preservative during storage.

Other optional ingredients include a solvent in an amount from about 0.5 to 3.0 percent-by-weight, such as propylene glycol to maintain the composition in a liquid state to avoid plugging of the spray nozzle tip during application. Pigment for adding color can also be incorporated into the composition if a tracer or marker is desired when spraying large surface areas. This assists in readily tracking treated areas, and thereby avoiding missing or oversraying areas already treated. A silicon dioxide flattening agent can also be added if a surface without sheen is desired. It will be understood the above optional ingredients and the amounts employed will be apparent to persons of ordinary skill in this art.

As previously discussed, as an alternative embodiment, the present invention contemplates a combination composition which serves as a long term protective barrier to building/construction materials, but also contains other ingredients for cleaning and remediating such building/construction materials already contaminated with fungi, such as mold, mildew, yeasts and/or other microorganisms, e.g., bacteria. This allows for both prompt remediation of the affected materials, while also providing protection from mold/mildew from returning, as well as a protective barrier coating against future development of such microorganisms. In this connection, the present invention includes the key active ingredients of the solutions of U.S. Pat. No. 6,530,384 to Meyers et al., the contents of which are incorporated herein by reference.

The foregoing protective barrier solutions can therefore have as further active ingredients taught by Meyers et al, namely a quaternary ammonium compound and hydrogen peroxide. The barrier coating compositions already contain a surfactant, e.g., nonionic surface active agent, so further surfactant is not actually necessary. Hydrogen peroxide is incorporated into the barrier coating compositions generally in a range from 0.002 to about 0.04 percent-by-weight based on concentrated solutions, e.g., 30 or 40 percent-by-weight. Disinfectant quaternary ammonium compound, such as dialkyl-dimethyl ammonium chloride, or other quaternary ammonium compound can be added in an amount generally ranging from about 0.002 to about 0.04 percent-by-weight.

The additional additives, namely hydrogen peroxide and disinfectant quaternary ammonium compound enhances the spectrum of activity as a bactericide. That is, the compositions of the invention may have further additives for a broader spectrum of biocidal activity. In this regard, the introduction of hydrogen peroxide and disinfectant quaternary ammonium compound or salt thereof in combination with other surfactant, e.g., nonionic surface active agent previously discussed enhances the biocidal activity of the barrier solutions of the invention to achieve a “virtual 100% kill” of bacteria and fungi infected substrates in accordance with the teachings of Meyers et al (U.S. Pat. No. 6,530,384). The solutions of Meyers et al are commercially available under the registered Trademark “Anabec” available from Anabec, Inc., Clarence, N.Y.

The compositions of this invention may be applied to porous surfaces by various methods, including by brush or roller mechanism. However, it is most desirable to apply the solutions of the invention by means of conventional sprayer, e.g., airless paint sprayer. As previously disclosed, the compositions can be applied to a variety of substrates, e.g., unfinished wood products used in building construction, brick, block and sheetrock (drywall), to name but a few.

In order to illustrate the various embodiments of the barrier/sealer compositions and to demonstrate methods of using the formulations the following performance studies were performed:

EXAMPLE 1

The following formulation for a protective barrier solution was prepared: Tributyl phosphate plasticizer 1-3% *Metasol TK 100LC fungicide  0.2-0.06 Biocheck 410 0.04-0.05 Propylene glycol  0.5-2.0 Nonionic surfactant  0.6-2.0 Rheology Modifier  1.5-3.0 Ammonia to pH 7 Paraffin oil  2.0-4.0 Vinyl acrylic latex 40.0-50.0 Water to 100% *2-(4-thiazoyl)benzimidazole (Nalco Chem. Co., Naperville, IL)

The above aqueous protective barrier compositions were prepared by first mixing all the ingredients into the water, except the vinyl acrylic latex. After the aqueous mixture was formed the vinyl acrylic latex was added as a final ingredient.

The above sealer/barrier compositions were tested to determine the performance of dry-films as protective sealers in preventing the development of mildew during testing on porous cellulosic substrates. Several test samples of the composition were prepared with levels of fungicide ranging from 250 ppm to 3000 ppm. In addition, a composition was prepared without fungicide for use as a control.

Individual samples of the sealer/barrier composition were weighed out. Fungicide was added to the samples of the sealer/barrier coating compositions in a ladder series of levels (e.g., 250, 500, 750 1000 ppm, etc.) and thoroughly mixed. The test porous cellulosic substrates consisting of Whatman No. 30 filter paper were first brush coated each with two (2) coats of test composition, and allowed to dry in a protected location. Duplicate two inch squares were then cut from the coated filter paper specimens and placed on the surface on malt agar petri plates.

Test inoculums consisting of aqueous spore suspensions at a concentrations of ˜10⁵ spores were prepared in sterile water. Those films (compositions) which were intended for use in interior application were inoculated with a mixture of Aspergillus niger (ATCC 6275) and Penicillium pinophilum (ATCC 9644). Films intended for exterior application were inoculated with Aureobasidium pullulans (ATCC 9348). The samples were inoculated by spraying the fungal spore suspensions on the test specimens, in the form of a fine mist.

The testing protocols were accelerated by incubating all inoculated samples at 28 to 30° C. for a period of two (2) weeks. The samples were visually observed after periods of 7 days and 14 days of incubation with the results shown below in the following Table: TABLE BIOCIDE LEVEL (ppm) 7 DAYS 14 DAYS Control 0 0 1 Sample 1 250 0 0 Sample 2 500 0 0 Sample 3 750 0 0 Sample 4 1000 0 0 Sample 5 1500 0 0 Sample 6 2000 0 0 Sample 7 2500 0 0 Sample 8 3000 0 0 0 = No mold growth 1 = Trace mold growth 2 = Light mold growth 3 = Moderate mold growth 4 = Heavy mold growth

The test data demonstrates that as little as 250 ppm of the biocide is capable of preventing mold development on the substrate.

EXAMPLE 2

The following combination formulation was prepared for remediation of substrates having mold/mildew and protected from reinfection and long term protection from mold/mildew/bacterial infestation: Tributyl phosphate plasticizer 0.25-1.0% Metasol TK 100LC fungicide  0.005-0.01 Biocheck 410 0.0125-0.05 Propylene glycol  0.12-0.4 Nonionic surfactant  0.12-0.5 Rheology Modifier   0.3-0.5 Ammonia to pH 7 Paraffin oil   0.5-1.5 Vinyl acrylic latex  10.0-15.0 Quaternary Ammonium Compound 80  0.005-0.01 Hydrogen peroxide  0.005-0.1 Igepal optical brightener  0.005-0.1 Water to 100%

The above aqueous protective biocidal barrier compositions was prepared by first mixing all the ingredients into the water, except the vinyl acrylic latex. After the mixture was formed the vinyl acrylic latex was added as a final ingredient. 

1. A protective barrier composition for porous substrates, which comprises an antimicrobial agent, a plasticizer, a surfactant, a continuous film forming polymer and a water repellent compound.
 2. The protective barrier composition of claim 1, wherein the antimicrobial agent comprises at least a fungicidal agent, the surfactant is a nonionic surface active agent, the continuous film forming polymer is a water based vinyl resin and the water repellent compound is a waxy compound.
 3. The protective barrier composition of claim 2, wherein said at least a fungicidal agent is a benzimidazole, the continuous film forming polymer is a vinyl acrylic latex, the waxy compound is a paraffin oil, and the pH of the composition is adjusted to about 7.0.
 4. A protective barrier composition for porous substrates, which comprises a benzimidazole fungicidal agent, hydrogen peroxide, a quaternary ammonium compound, a plasticizer, a nonionic surfactant, a continuous film forming polymer in combination with a waxy water repellent compound.
 5. The protective barrier composition of claim 4, which is an aqueous solution comprising from about 0.01 to about 0.10 percent-by-weight of said benzimidazole fungicidal agent; from about 0.002 to about 0.04 percent-by-weight of said hydrogen peroxide; from about 0.05 to about 5.0 percent-by-weight of said quaternary ammonium compound; from about 0.10 to about 3.0 percent-by-weight of said nonionic surfactant, from about 0.50 to about 4.0 percent-by-weight of said plasticizer; from about 30 to about 60 percent-by-weight of said continuous film forming polymer and from about 2 to about 4 percent-by-weight of said waxy water repellent compound.
 6. A method for protecting a porous substrate from the development of at least one member selected from the group consisting of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 1. 7. A method for protecting a porous substrate from the development of at least one member selected from the group consisting of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 2. 8. A method for protecting a porous substrate from the development of at least one member selected from the group consisting of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 3. 9. A method for protecting a porous substrate from the development of at least one member selected from the group consisting of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 4. 10. A method for protecting a porous substrate from the development of at least one member selected from the group consisting of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 5. 11. A method for treating a porous substrate having at least one member selected from the group consisting of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 1. 12. A method for treating a porous substrate having at least one of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 2. 13. A method for treating a porous substrate having at least one of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 3. 14. A method for treating a porous substrate having at least one of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 4. 15. A method for treating a porous substrate having at least one of mold, mildew and bacterial infestation, which comprises the step of contacting said substrate with an effective amount of the protective barrier composition of claim
 5. 